EV vs Petrol Cost Calculator UK
Find out if switching to electric will save you money — personalised to your actual driving and charging habits.
How does the EV vs petrol calculator work?
The calculator estimates annual fuel/energy cost for your current petrol or diesel car and for an equivalent EV, then adds typical servicing and road tax figures for each to reach a total annual cost you can compare directly. The EV side blends your home and public charging rates according to the percentage you set on the slider, since almost no driver charges 100% in one place — this blended-rate approach is what makes the comparison realistic rather than a best-case-only number.
Petrol/diesel cost uses your MPG converted to litres (1 UK gallon = 4.546 litres) multiplied by fuel price. EV cost uses your mileage divided by mi/kWh efficiency, multiplied by your blended electricity rate.
Purchase price and depreciation aren't included. This calculator answers "which is cheaper to run day-to-day," not "which is cheaper overall" — EVs typically cost more to buy new, though the gap narrows on the used market. Factor in the purchase price difference separately when deciding whether to switch.
3 worked examples
Example 1 — Mostly home charging, average mileage
A driver who charges 90% at home overnight, comparing against a 35 MPG petrol car at average UK mileage.
8,000 miles/year · petrol 35 MPG @ 157p/litre · EV 3.5 mi/kWh · home 27p/kWh, public 75p/kWh · 90% home charging
Petrol fuel cost:(8,000 ÷ 35) × 4.546 × £1.57 = £1,631/year
Blended EV rate:(0.9 × 27p) + (0.1 × 75p) = 24.3p + 7.5p = 31.8p/kWh
EV energy cost:(8,000 ÷ 3.5) × £0.318 = £727/year
Result:Petrol total ≈ £2,176 (fuel + £350 servicing + £195 tax) vs EV total ≈ £1,252 (energy + £130 servicing + £195 tax) — saving of ≈£924/year.
Example 2 — 50/50 mixed charging, higher mileage commuter
A commuter with no reliable home charger access some nights, splitting evenly between home and public charging, at higher annual mileage.
14,000 miles/year · petrol 42 MPG @ 157p/litre · EV 3.8 mi/kWh · home 27p/kWh, public 75p/kWh · 50% home charging
Petrol fuel cost:(14,000 ÷ 42) × 4.546 × £1.57 = £2,378/year
Blended EV rate:(0.5 × 27p) + (0.5 × 75p) = 13.5p + 37.5p = 51p/kWh
EV energy cost:(14,000 ÷ 3.8) × £0.51 = £1,879/year
Result:Petrol total ≈ £2,923 vs EV total ≈ £2,204 — saving of ≈£719/year, noticeably smaller than Example 1 purely because of the heavier public charging mix.
Example 3 — No home charging, all public (the charging trap)
A driver without home charging access — street parking, no driveway — relying entirely on public chargers, often at rapid/motorway rates.
8,000 miles/year · petrol 40 MPG @ 157p/litre · EV 3.5 mi/kWh · public-only at 75p/kWh · 0% home charging
Petrol fuel cost:(8,000 ÷ 40) × 4.546 × £1.57 = £1,427/year
EV energy cost (100% public):(8,000 ÷ 3.5) × £0.75 = £1,714/year
Result:Petrol total ≈ £1,972 vs EV total ≈ £2,239 — the EV actually costs ≈£267/year more once servicing and tax are added on both sides. This is the "public charging trap" — without home charging, the EV cost advantage can disappear entirely.
The difference between Example 1 and Example 3 is charging location alone — same mileage, similar efficiency. Your % home charging is the single biggest lever in this calculator. If you can't charge at home, the EV cost case weakens substantially and depends heavily on finding a cheap public tariff.
Home vs public charging costs explained
Home charging remains the most economical way to run an EV. Most drivers charge overnight using a dedicated 7kW home charger (wallbox), which adds approximately 30 miles of range per hour. Smart electricity tariffs like Octopus Go offer off-peak rates from as low as 7–10p/kWh during overnight hours, making home-charged EVs exceptionally cheap to run.
Public charging is more expensive. Destination chargers (at car parks, supermarkets) typically cost 35–55p/kWh, while motorway rapid chargers (50–350kW) from providers like BP Pulse or Gridserve range from 60–85p/kWh.
| Charging type | Cost per kWh | Notes |
|---|---|---|
| Home — overnight EV tariff | 7–15p | Cheapest option; requires a smart meter and EV tariff |
| Home — standard tariff | 24–27p | Default rate if not on an EV-specific tariff |
| Workplace charger | Free–30p | Varies enormously by employer |
| Public destination (AC) | 30–45p | Car parks, supermarkets, retail |
| Public rapid (DC) | 45–65p | Faster charging, higher cost |
| Motorway ultra-rapid | 65–85p | Most expensive; can exceed petrol cost per mile |
Electric car road tax — what changed in April 2025?
EVs registered on or after 1 April 2025 now pay Vehicle Excise Duty (VED) — road tax — for the first time. The standard rate of £195 per year applies from the second year of registration. New EVs also pay a first-year rate (currently £10) and are subject to the expensive car supplement (an additional £410/year for 5 years) if their list price exceeds £40,000.
This change removed the VED exemption that EVs had previously enjoyed, though they remain exempt from London's Congestion Charge for now. See our full UK Road Tax Explained 2026 guide for every rate band.
Common calculation mistakes
Assuming 100% home charging when the reality is mixed
The single most common overestimate of EV savings comes from assuming every charge happens at the cheap home rate. Be honest about your real charging mix — even drivers with home chargers often top up in public occasionally, and Example 2 above shows how much a 50/50 split changes the result versus Example 1's 90/10.
Comparing against manufacturer-claimed MPG or WLTP range
Both petrol MPG and EV WLTP efficiency figures are lab-tested and typically 10–25% more optimistic than real-world driving, especially at motorway speeds and in cold weather. Use real-world figures from owner communities (Fuelly, Honest John, Zapmap) rather than the official spec sheet.
Ignoring the public charging trap entirely
As Example 3 shows, an EV genuinely can cost more than petrol per mile for drivers without home charging access who rely on motorway rapid chargers. Don't assume electric is automatically cheaper — run the actual numbers for your charging reality first.
Not accounting for the road tax change since April 2025
Older comparisons and some online calculators still show EVs as VED-exempt. That changed in April 2025 — EVs now pay the same £195/year standard rate as petrol cars, which slightly narrows the EV cost advantage compared to pre-2025 comparisons.
Ways to maximise EV savings
- Switch to an EV-specific overnight tariff (e.g. Octopus Go, OVO EV Everywhere) — can cut home charging cost to 7–15p/kWh from a standard 24–27p/kWh
- Check if your workplace offers free or subsidised charging — many employers now provide this as a benefit
- Plan longer trips around cheaper charging stops rather than defaulting to the nearest motorway rapid charger
- Install a home charger if you have off-street parking — the £800–£1,200 cost typically pays for itself within 1–2 years for an average-mileage driver
- Compare EV-specific insurance quotes rather than assuming your existing insurer's standard rate — specialist EV insurers are increasingly competitive
How we calculate
Petrol/diesel cost = (Annual mileage ÷ MPG) × 4.546 × fuel price per litre
Blended EV rate = (% home ÷ 100 × home rate) + ((100 − % home) ÷ 100 × public rate)
EV energy cost = (Annual mileage ÷ mi/kWh) × blended rate
Each side's total adds a fixed servicing average (£350/year petrol, £130/year EV, based on typical annual service and repair cost data) and the current standard VED rate (£195/year for both, since April 2025). The saving or extra cost shown is simply petrol total minus EV total. Purchase price, depreciation, insurance, and home charger installation are deliberately excluded — see the hidden costs section above to factor those in yourself.
Frequently asked questions
Are electric cars actually cheaper to run in the UK in 2026?
For most drivers who charge primarily at home, yes — typically saving several hundred to over a thousand pounds a year versus an equivalent petrol car. But the saving depends heavily on your home-vs-public charging mix; drivers without home charging access can find the cost advantage shrinks or disappears.
What's the best electricity tariff for EV charging?
EV-specific overnight tariffs like Octopus Go or OVO EV Everywhere typically offer rates of 7–15p/kWh during off-peak hours, roughly half the standard rate. If you charge mostly overnight at home, switching to one of these tariffs is usually the single biggest lever on your running costs.
Does the April 2025 EV road tax change affect the savings picture?
Slightly. EVs now pay the same £195/year standard VED as petrol cars (previously they were exempt), which narrows the EV cost advantage by that amount compared to older, pre-2025 comparisons. It doesn't change the underlying fuel/energy cost saving, which remains the larger factor.
How much does a home EV charger cost to install?
A standard 7kW home wallbox typically costs £800–£1,200 fully installed, including any necessary electrical work. This is a one-off cost not included in the running-cost calculator above, but it's usually essential to realising the home-charging savings shown.
Is an EV still cheaper if I can't charge at home?
Not necessarily. If you rely entirely on public rapid or motorway chargers (60–85p/kWh), the cost per mile can match or exceed a petrol car's, as shown in Example 3 above. Public-only EV charging can still make sense for other reasons (emissions, driving experience), but the pure running-cost case is much weaker without home charging.
References & data sources
- GOV.UK — Vehicle tax rate tables. Current 2026 VED rates for both petrol/diesel and electric vehicles, including the April 2025 EV road tax change and the expensive car supplement.
- Ofgem — Energy Price Cap and unit rates. Home electricity unit rate data used as the calculator's default home charging rate.
- Zapmap — UK public charging cost data. Public and rapid charging price ranges used as the calculator's default public charging rate and in the home-vs-public comparison table.
- RAC Foundation — Fuel price data and motoring cost analysis. UK average petrol and diesel prices used as the calculator's default fuel price.
Figures reflect UK national averages as of May 2026. Electricity tariffs, fuel prices, and public charging rates all change frequently — always check current pricing before making a purchase decision based on this calculator alone.